Robyn Freeman-Key has joined the list of the walking wounded after a spate of accidents at racetracks in the past week.

Freeman-Key will need surgery on a fractured cheekbone suffered in an incident behind the barriers at Hawkesbury on Saturday.

"Robyn has shattered her cheekbone and will need reconstructive surgery next week on her cheekbone and her teeth, which have been displaced," Racing NSW safety officer Maurice Logue said.

The week began badly when Peter Mertens and Jordan Childs came down in a two-horse fall at Hamilton on Monday.

Childs broke both wrists but did not require surgery while Mertens was not so lucky.

He has a punctured lung, broken ribs, a broken collarbone and a fractured ankle and faces some months on the sidelines.

Kathy O'Hara will also spend some time out after suffering a concussion when she came off her horse at Randwick on Friday and was kicked in the head by a following runner.

O'Hara required stitches to a gash on her head but it could have been much worse.

"It looked very bad," deputy chief steward Greg Rudolph said.

"Kathy will have to undergo a range of tests before she can ride again and also get a clearance from a neurosurgeon.

"That's the procedure with all head injuries."

Just a day after O'Hara's fall, her jockey sister Tracy suffered ligament damage to an ankle when she came off her horse in a race at Gladstone in Queensland.

Victorian apprentice Ryan Hurdle has a broken collarbone from a fall at Pakenham on Thursday while fellow junior rider Yusuke Ichikawa dislocated his shoulder at Randwick on Friday when he was passing his whip through from one hand to the other.

One fall which didn't have the dire consequences it looked as if it might happened at at Bendigo on Wednesday when veteran Darren Gauci slipped off near the winning post when he lost an iron.

Cleared of a broken wrist, Gauci was at Cranbourne on Saturday night where he his one ride, Esprit's Choice, was a winner.

His five rides at Wodonga on Sunday produced two minor placings.